The disclosure herein relates generally to apparatus for protecting circuitry from moisture ingress, and further to fabrication methods for constructing such apparatus.
Electrical circuits (e.g., integrated circuits) include many types of active and passive devices (e.g., transistors, capacitors, resistors, etc.) that may be subject to damage from moisture (e.g., corrosion and functional changes to the system). For example, moisture may affect the operation and performance of circuitry, such as sensitive circuits used in implantable medical devices (e.g., sensor circuitry, pacing circuitry, timing circuitry, etc.). One way to mitigate such moisture issues is to protect such circuits using a moisture barrier.
Various attempts have previously been made to seal the interior of semiconductor device dies from moisture ingress. The bottom substrate in many semiconductor devices (e.g., silicon) effectively blocks moisture from entering the interior of the die from the bottom, but materials commonly employed in fabricating further layers above the substrate may provide a path for moisture to enter from the top and/or sides of the die after separation. For example, certain commonly employed insulator materials such as silicon oxide (SiO) may be penetrated by moisture. Accordingly, lateral or side seal structures have been provided between the die edges and the active region. Such side seal structures, e.g., may be formed in one or more layers in the processed semiconductor device using vertically oriented contacts (e.g., such as tungsten) and metal die seal structures.
For example, an upper seal layer is described in U.S. Pat. No. 6,566,736 entitled “DIE SEAL FOR SEMICONDUCTOR DEVICE MOISTURE PROTECTION,” issued on May 20, 2003, which allegedly provides a vertical moisture seal.